There is a discussion in the 3GPP (3rd Generation Partnership Project) RAN-WG on a home base station HNB employing the “LTE (Long Term Evolution)” as a radio access scheme.
Specifically, in the current 3GPP specifications, a mobile communication system is configured to manage a specific mobile station (a mobile station permitted to select a specific cell as a camped cell) belonging to a CSG (Closed Subscriber Group) under control of the home base station HNB.
In other words, in the current 3GPP specifications, only a specific mobile station belonging to a CSG can perform communication via a CSG cell (specific cell) under control of the home base station HNB.
However, the current 3GPP specifications do not define a method in which the mobile station selects a camped cell in an environment where CSG cells and macro cells coexist.
Accordingly, the following situation may occur. Specifically, even when a mobile station using a macro cell as a camped cell enters an area where a CSG cell regarding the mobile station as a specific mobile station is selectable as a camped cell, the mobile station cannot detect that, and thus cannot change the camped cell to the CSG cell.
The present invention has been made in consideration of the above problem, and has an objective to provide a cell selection method and a mobile station that allow a camped cell to be properly selected in an environment where CSG cells and macro cells coexist.